Hello @juancamawey,
I think you misread the notice in your admin plugin list. ACF Extended is an extension of ACF Pro (which is an another plugin), this is why it requires Advanced Custom Fields PRO 5.8 (at least), as described in the plugin main description and requirements section.
This plugin requires at least ACF Pro 5.8. If you don’t already own ACF Pro, you should consider it. It’s one of the most powerful WordPress plugin available
You probably didn’t activate ACF Pro on your website, since it says that you need “ACF Pro” (and not “ACF Extended Pro”). So you don’t need any upgrade, just the base plugin. Once you enable it, you’ll be able to enjoy ACF Extended and its hundred free features.
As it seems to be a simple misunderstanding, would you like to please reconsider your review?
Have a nice day!
Regards.